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Ch4/Hadron Structure. 核民主?. 六十年代初发现许多不稳定粒子( hadrons,resonance), 需分类(见下页） 有没有联系?更高的对称性? Isospin  一种 nucleon, pion, Sigma 近似地是同一种粒子的不同状态？(自旋,宇称相同) 推广同位旋概念--》（破缺的）幺正对称性 粒子按不可约表示分类，每个粒子对应一个分量. Baryon Summary. SU(3) 理论. 坂田模型： 所有强子由 p,n,Lamda 和其反粒子组成 p,n,Lamda 构成 SU(3) 三维基础表示 介子 由一对正反基础重子组成 - PowerPoint PPT Presentation

(,)--

• Baryon Summary

• SU(3)p,n,Lamdap,n,LamdaSU(3)

/

• Eight-fold way1961Neuman and Gell-MannSU(3)

:(81/2+,93/2+)

10* 27

• SU(4) multiplets of baryons

• The Omega Quantum num B=1, I=0, S= -3, Q= -1The mass

• Weak DecayOmega

10^(-10)

1964OmegaSU(3)

• Quark Model1964Gell-Mann and Zweig(q-qbar)(qqq) (next page)Gell-Mann-Nishijima

• Quark Sub-structureMesons and Baryons:

Note: 10* and 27 dont appear

• Multiplets (figures)

• Color

10omega)SU(3)

• Every naturally occurring particle is a color singlet!

• (so as meson)

Protons magnetic moment

• (n/p=-2/3)

baryonmomentcalcexptp2.792.793n-1.86-1.913-0.58-0.612.682.33+-0.130.82-1.05-1.41+-0.25-1.40-1.25+-0.01-0.47-0.69+-0.04

• Constituent quark-(hyperfine)see LQCD spectrum)

For 3 equal masses,

• QCDmp=938.27MeV (uud)mn=939.56563MeV (udd)mp=139.56995MeV (ud, ud)mK=493.677MeV (us, us)Lattice QCD10%

• 3 Equal Masses

• (in MeV)Using m_u=363,m_s=538,C=4m_u^2*50

BaryonCalcExptN939939Lambda11161114Sigma11791193Xi13271318Delta12391232Sigma*13811384Xi*15291533Omega16821672

• J,PI,I_3,Y)Gell-Mann-Okubo() --

--KG Eq)b=0

• eta609

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